Authorities detained 17 people who were developing four separate potential attacks aimed at Saudi Arabians.
The explosion took place as several recruits were lining up at a military base in the southern city of Mukalla.
The blast at a popular tourist area in the city comes just days after a suicide attack killed 37 people in the capital of Ankara.
The trial is the first in recent memory for Saudis accused of spying and may stoke tensions between local Shiite and Sunni Muslims, and with Iran.
Mass shootings like the one that occurred Thursday are a rare occurrence in Saudi Arabia.
A New Year's Eve blaze ignited in the 63-story the Address Downtown Dubai hotel ahead of a fireworks event.
The municipal ballot will be the first since late King Abdullah bin Abdulaziz Al Saud's 2011 decree allowing women to vote and run.
The bodies of at least 100 people already have been recovered after a Russian airliner carrying 217 passengers and 7 crew members crashed in the Sinai region Saturday.
King Salman last month decreed that victims of the deadly crane collapse should each receive 1 million riyals, about $266,705.
Saudi authorities discovered 70,000 forged Qurans on Monday in the latest event in a hajj season beset with misfortune.
Policy changes also include a lowering of the minimum voting age from 21 to 18.
Last week, Israel reportedly hit a convoy carrying long-range Scud missiles destined for Hezbollah.
Izzat Ibrahim al Douri led an insurgent group that contributed to the rise of ISIS.
After pounding Houthi rebels in Yemen from the air, the Saudi Arabia-led coalition is expected to take the fight to the ground.
Abdel Fattah al-Sisi says it is crucial to tackle extremist ideologues across the region.
Egypt has announced that a ground invasion of Yemen is forthcoming, and over 150,000 Saudi troops have reportedly been mobilized.
As a child, Mohammed Emwazi immigrated from Kuwait, where he and his family may not have had citizenship.
Egypt's Sisi vowed to avenge the killings of the members of the oft-persecuted Christian sect. President Obama condemned the killings.
Nabil al-Fadhl said he is facing charges of insulting the nation after supporting the legal sale of alcohol.
Lebanese officials claimed that al-Baghdadi's daughter and ex-wife were among those detained near a Syrian border crossing.
In one of the deadliest attacks since Mohammed Morsi was ousted, gunmen attacked a checkpoint with rocket-propelled grenades and machine gun.
A man inside the Duroy Hotel in Beirut, Lebanon blew himself up during a security raid Wednesday.